Abstract: China and the United States are the most important economies in the world, so to some extent their trade and friction would have great effect on world economy. In recent years, the Sino-US trade boomed under the keynote of mutual benefit,while the trade surplus increased rapidly. Under this tendency, the US Commerce Department did the "trade investigation" unilaterally in April 2018, and then, the trade friction between Sino and US broke out. To what extent would the Sino-US trade friction influence China's economy and employment? How does the export decline conduct and spread via economic network of "investment, production, supply and demand"? What should China do to deal with unilateral trade protectionism of US and accelerate the economic transition? In order to answer these questions, the imperfect substitute import demand model is firstly bulit to measure the impact of adding tariff on China's export by calculating the import demand elasticity of commodity in each sector. Meanwhile, the coupling relationship of "production, investment, and consumption" in macro economy system is considered, and the impact of China's export decline on trade value added and employment is measured by partially closed input-occupancy-output model with partially endogenous investment and consumption, that built based on the input-occupancy-output technique. The combination of these above two models makes the change in export resulting from change in tariff and its impact on national economic system be measured exactly. Based on the new model,the short-term comprehensive impact of the US unilaterally on China's 25% import tariffs on related commodities in 50 billion and 200 billion dollar scenarios is studied. In both scenarios, it is found China's exports to the United States will fall by 4.27% and 16.03%. Our results show that the China's value added of domestic trade exports lost 96.29billion yuan and 382.99 billion yuan, the domestic employment decreased by 0.79 million and 3.31million, respectively.The emerging ICT industries, represented by advanced equipment, information and communication technology, and computers, are directly affected.The upstream and downstream industries with high correlation with the ICT industry will also be significantly affected.In the context of frequent trade frictions between China and the United States,China may face deflation from export deflation and unemployment in related industries.Under the trade friction, China needs to actively upgrade domestic consumption levels and optimize investment structure.

Key words: Sino-US trade friction, imperfect substitute import demand model, input-occupancy-output model, export value-added, employment